Originally Posted by
Derailed
Um... you're talking about electronic effects, right? Very small changes in composition most certainly can dramatically affect electronic characteristics -- the crystal structure is not as important as electronic structure. (I know very little about metallurgy -- you may well be right in this specific case -- but I think it is silly to dismiss a concern about the effect of changing the composition because, allegedly, the crystal structure is the same. If that were a reasonable argument, wouldn't it negate much of what is known about semiconductors?)
Compare and contrast the conductivity of metals with by definition, overlapping valence and conduction bands, and semiconductors, with their
several orders of magnitude less charge carriers. In the case of solid solutions in metal, the minor alteration in lattice parameter with other metals with similar valence, in the case epecially of Ti alloys is the controlling factor. In the case of silicon, or gallium arsenide, you'd be doping a very poor conductor with electron sinks or providers, grossly atering electronic behaviour with just a few ppm impurity, but only because the material is instrinisically piss-awful at conducting.